Complete Genome Sequence of Recombinant Porcine Circovirus Type 2 Strain SD-3

We report here the genome sequence of a recombinant porcine circovirus type 2 strain SD-3, isolated from a commercial swine farm with an outbreak of postweaning multisystemic wasting syndrome (PMWS) in pigs in Shandong Province of China. The complete circular genome of this isolate is 1,767 nucleotides in length. This recombinant isolate has the ORF1 regions from PCV2a viruses and ORF2 regions from PCV2b. The findings will help us to understand the molecular evolution of porcine circovirus type 2 and the relationship between porcine circovirus type 2 and disease.     

猪圆环病毒2型与猪细小病毒共感染对猪肺泡巨噬细胞吞噬功能及其干扰素表达水平的影响

【目的】分析猪圆环病毒2型(PCV2)与猪细小病毒(PPV)共感染对猪肺泡巨噬细胞(PAM)吞噬功能及其干扰素表达水平的影响,为进一步阐明猪断奶后多系统衰减综合征的发病机制提供实验依据。【方法】将48头5周龄健康仔猪随机分为PCV2组、PPV组、PCV2/PPV组和对照组,每组12头。PCV2和PPV组经口鼻途径分别接种PCV2或PPV,PCV2/PPV组同时接种PCV2和PPV,对照组接种细胞营养液。感染后3、7、14和35d(dpi)从每组随机选择3头剖杀,检测PAM的存活率、吞噬活性及其α1型干扰素(IFN-α1)、γ干扰素(IFN-γ)mRNA的表达水平。【结果】PCV2组和PCV2/PPV组PAM的存活率于3、7、14dpi均低于对照组,35dpi均与对照组PAM的存活率接近,PCV2与PCV2/PPV两组之间差异不显著(P>0.05);3个病毒感染组PAM的吞噬功能均显著下降(P<0.01),其中PCV2/PPV组的吞噬功能低于PCV2组(P<0.05);PCV2/PPV组PAM中IFN-α1和IFN-γ mRNA的水平持续低于PCV2、PPV组和对照组的水平(P<0.01)。【结论】PCV2与PPV共感染没有引起PAM的活力进一步下降,但导致其吞噬功能及IFN-α1和IFN-γmRNA的表达水平持续降低。     

Complete genome sequence of a novel field strain of rearranged porcine circovirus type 2 in southern china

We report here the complete genomic sequence of a novel porcine circovirus type 2 (PCV2) strain, which is supposed to be the result of natural genetic recombination between the ORF1 gene of genotype PCV2b-1B and the ORF2 gene of PCV2b-1C. Further analyses revealed that this novel PCV2 strain arose from recombination between PCV2a and PCV2b strains within the ORF2 gene. To our knowledge, this is the first report of both inter- and intragenotype PCV2 gene rearrangement in the field, and it will help in understanding the epidemiology and molecular characteristics of porcine circovirus type 2(PCV2) in southern China.     

Detection of porcine circovirus type 1 in commercial porcine vaccines by loop-mediated isothermal amplification

A loop-mediated isothermal amplification (LAMP) method with a real-time monitoring system was developed for the detection of porcine circovirus type 1 (PCV1) in commercial swine vaccines. This method was highly specific for PCV1. No cross-reaction to porcine circovirus type 2, porcine parvovirus, pseudorabies virus, classical swine fever virus, and porcine reproductive and respiratory syndrome virus was observed. The analytical sensitivity of the LAMP for PCV1 DNA was 10 copies/μl in the case of positive recombinant plasmid comparable to that obtained from the nested polymerase chain reaction (nested PCR). Furthermore, 25 commercial swine vaccines were tested by both the LAMP and the nested PCR, and three of them were tested positive for PCV1 DNA. These results indicate that PCV1 DNA can be real-time detected by the LAMP; the method was highly specific, sensitive, and rapid for the detection of PCV1 DNA, particularly in commercial swine vaccines.     

Rapid detection of porcine circovirus type 2 using a TaqMan-based real-time PCR

Porcine circovirus type 2 (PCV2) and the associated disease postweaning multisystemic wasting syndrome (PMWS) have caused heavy losses in global agriculture in recent decades. Rapid detection of PCV2 is very important for the effective prophylaxis and treatment of PMWS. To establish a sensitive, specific assay for the detection and quantitation of PCV2, we designed and synthesized specific primers and a probe in the open reading frame 2. The assay had a wide dynamic range with excellent linearity and reliable reproducibility, and detected between 102 and 1010 copies of the genomic DNA per reaction. The coefficient of variation for Ct values varied from 0.59% to 1.05% in the same assay and from 1.9% to 4.2% in 10 different assays. The assay did not cross-react with porcine circovirus type 1, porcine reproductive and respiratory, porcine epidemic diarrhea, transmissible gastroenteritis of pigs and rotavirus. The limits of detection and quantitation were 10 and 100 copies, respectively. Using the established real-time PCR system, 39 of the 40 samples we tested were detected as positive.     

嵌合猪圆环病毒PCV1-2的构建及其感染性初步鉴定

猪Ⅱ型圆环病毒(PCV2)是当前严重危害养猪业的重要病原之一。目前,世界上还没有有效疫苗用于该病毒的免疫预防。该研究利用PCR方法,将PCV2的ORF2基因替换猪Ⅰ型圆环病毒(PCV1)的ORF2基因,构建了以PCV1基因组为骨架的嵌合病毒(PCV1-2)分子克隆(pSK2PCV1-2)。将该分子克隆转染PK-15细胞并连续盲传5代,用RT-PCR方法可以在转染后盲传的细胞中检测到PCV1的ORF1 mRNA和PCV2的ORF2 mRNA,但检测不到PCV1的ORF2 mRNA和PCV2的ORF1 mRNA。间接免疫荧光检测显示在盲传第5代的细胞中有PCV2 ORF2蛋白的表达,表达蛋白主要分布于细胞核。该研究初步证实构建的PCV1-2分子克隆转染细胞后可以形成具有感染性的嵌合病毒,从而为更深入研究嵌合病毒生物学特性奠定了基础。     

Recombinant porcine norovirus identified from piglet with diarrhea

ABSTRACT: BACKGROUND: Noroviruses (NoVs) are members of the family Caliciviridae and are emerging enteric pathogens of humans and animals. Some porcine NoVs are genetically similar to human strains and are classified into GII, like most epidemic human NoVs. So far, PoNoV have been exclusively detected in fecal samples of adult pig without clinical signs. METHODS: We collected 12 fecal samples from piglets with diarrhea and no accurate diagnosis of etiology from three commercial pig farms in Shanghai suburb. We tested for PoNoV, porcine circovirus type 2, porcine rotavirus, porcine transmissible gastroenteritis virus, porcine sapovirus, and porcine epidemic diarrhea virus using RT-PCR method. The full-genome sequence of the PoNoV was then determined and analyzed. Experimental infection of miniature pigs with fecal suspensions was performed to make sure if this strain can cause gastroenteritis in piglets. RESULTS: Result showed that 2 of the 12 evaluated fecal samples were positive for PoNoVs, one of which was positive for PoNoV alone, and the other was coinfected with porcine circovirus and PoNoV. Phylogenetic and recombination analysis showed that the PoNoV positive alone strain was a recombinant new genotype strain. Experimental infection of miniature pigs with fecal suspensions confirmed that this strain can cause gastroenteritis in piglets. CONCLUSION: This is the first report that recombinant new genotype PoNoV exised in pig herd of China, which cause diarrhea in pigs in nature condition. This find raised questions about the putative epidemiologic role of PoNoV.     

Complete Genome Sequence of Porcine Circovirus 2d Strain GDYX

Porcine circovirus type 2 (PCV2) is the etiologic agent of porcine circovirus-associated disease, and it is mainly divided into five genotypes. Here, we report the complete genome sequence of PCV2 strain GDYX, which belongs to PCV2d and has a unique amino acid variation at position 169 (S to G).     

In vitro intragenomic rearrangement of porcine circovirus type 2

We report here for the first time the genome sequence of a rearranged porcine circovirus type 2 (PCV2) strain, CH-IVT1, isolated from PCV2-infected PK-15 cells. The complete circular genome of the CH-IVT1 is 605 nucleotides (nt) in length. The finding will help us to understand the molecular evolution of PCV2 and the relationship between PCV2 and PCV-associated diseases.     

Complete genome sequence of a highly prevalent porcine circovirus 2 isolated from piglet stool samples in China

Porcine circovirus type 2 (PCV2) is the etiologic agent of porcine circovirus-associated disease. Here, we first report the complete genome sequence of PCV2 strain JSTZ, which was isolated from piglet stool samples and is highly prevalent in China. It will help in understanding the epidemiology and molecular characteristics of PCV2.     

Astrovirus as a possible cause of congenital tremor type AII in piglets?

Background

Congenital tremor is associated with demyelination of the brain and spinal cord and is clinically noted as outbreaks of trembling and shaking in newborn piglets during a limited time-period. Six forms of the disease have been described, where form AII may be caused by an, as yet, unidentified viral infection. This study aimed to investigate the presence of astrovirus and circovirus by sequencing and polymerase chain reaction (PCR) analysis and by relating the findings to the occurrence of disease and lesions in the brain, in 4–6 days-old piglets obtained from a clinical outbreak of congenital tremor.

Results

In piglets with congenital tremor, there were mild to moderate vacuolar changes of the white matter in the cerebrum, brain stem and cerebellum. In healthy piglets, less conspicuous vacuolar changes were detected. One healthy and one diseased piglet were positive for porcine circovirus type 2. The nested pan-PCR showed the presence of astrovirus in at least one brain region in all piglets and by sequencing, two different porcine astrovirus lineages were identified.

Conclusions

The results do not support previous studies identifying porcine circovirus type 2 as the cause of congenital tremor. The demonstration of astrovirus in the brain of piglets suffering from congenital tremor is interesting. However, astrovirus was demonstrated in both healthy and diseased individuals and therefore, further studies are warranted to determine the possible involvement of astrovirus in the pathogenesis of congenital tremor in pigs.

     

A novel porcine circovirus type 2a strain, 10JS-2, with eleven-nucleotide insertions in the origin of genome replication

Here, we report a novel porcine circovirus type 2a (PCV2a) strain with 11 nucleotides (nt) inserted in the origin of genome replication (Ori). This is the first report of a PCV2a strain with nucleotide insertion in Ori. Our study will help further epidemiological studies and extend our knowledge of evolutionary characteristics of PCV2.     

猪圆环病毒3型衣壳蛋白(Cap)抑制宿主细胞天然免疫应答

【背景】猪圆环病毒是引起猪圆环病毒病的病原,能够引起严重的免疫抑制和临床症状,给养猪业造成严重的经济损失。【目的】研究猪圆环病毒3型(Porcinecircovirus3,PCV3)衣壳蛋白(Capsid protein,Cap)对宿主天然免疫应答的调控作用,解析其免疫抑制机制对阐明猪圆环病毒致病机制具有重要意义。【方法】通过构建Cap真核表达质粒,利用Westernblotting进行表达验证,实时荧光定量(RT-PCR)、双荧光素酶基因报告系统和ELISA探究Cap对I型干扰素通路活化的影响,通过免疫共沉淀探索其作用机制。【结果】真核表达质粒成功表达并且证实Cap可以抑制DNA模拟物Poly(dA:dT)诱导的I型干扰素通路的活化;Cap可以与天然免疫通路节点分子MITA相互作用。【结论】研究发现PCV3病毒Cap蛋白与干扰素通路节点分子MITA相互作用发挥免疫抑制作用,这为阐明PCV3免疫抑制机制提供了理论依据。     

Complete Genome Sequence of a Novel Porcine Circovirus Type 2b Variant Present in Cases of Vaccine Failures in the United States

Two genomes of a new porcine circovirus type 2 (PCV2) strain associated with cases of perceived failure of PCV2 vaccination were sequenced and analyzed. Based on the genome, this is the first report of this mutant of PCV2b in the United States. The genomic knowledge of this mutant PCV2b will improve understanding of the epidemiology of PCV and potentially inform the development of new and more effective vaccines for PCV2.     

猪圆环病毒2型、猪繁殖与呼吸综合征病毒及猪细小病毒混合感染的流行病学调查

根据GenBank上发表的PRRSVORF7、PPVVP2及PCV的基因组序列设计合成引物,建立了分别用于检测PRRSV、PPV和PCV的RT-PCR、PCR及复合PCR方法。应用建立的复合PCR方法对送检的127份病料进行了PCV的检测,对鉴定为PCV2阳性的67份病料再分别进行PRRSV和PPV的检测,以确定猪群中PCV2与PRRSV和,或PPV混合感染情况,结果表明,35份样品表现为PRRSV与PCV2混合感染,占样品总数的52．3％;18份样品表现为PCV2与PPV混合感染,占26．9％。另外,还有一定比例的三重感染,共5个样品,占7．5％。由此可见,猪群中PCV2与PRRSV及PPV混合感染比较普遍。     

In Vitro and In Vivo Isolation of a Novel Rearranged Porcine Circovirus Type 2

Here, we present the first report of a novel rearranged porcine circovirus type 2 (PCV2) strain named BIV, isolated from both in vitro and in vivo sources. The complete circular genome of BIV is 896 nucleotides in length. The data will help us to update current knowledge of the replication of PCV2 viruses in cell culture and of their molecular evolution, as well as their diagnosis.     

猪圆环病毒2型福建株的全基因组克隆与序列分析

根据GenBank上公布的猪圆环病毒2型全基因序列设计一对扩增PCV-2全基因的引物,建立扩增PCV-2全序列的PCR方法,并应用此方法从福建省不同地区采集的疑似断奶仔猪多系统衰竭综合征(PMWS)的仔猪肺组织病料中扩增出PCV-2全基因组(1 767 bp),将此基因片段克隆入pMD 18-T载体,筛选获得重组质粒pMD-PCV-2,并对其进行序列测定,然后对全基因组进行同源性和遗传进化分析。结果表明,福建省不同地区采集的猪肺组织扩增出的PCV-2全序列与GenBank上公布的的全基因组同源性介于94.9%-99.8%之间,ORF1的同源性介于97.2%-99.9%,ORF2的同源性也很高,介于97.7%-99.8%之间。其中福州株、福清株和漳州株与中国农大报道的12株、郑州株5株、杭州4株、武汉株3株、上海株2株、扬州2株、南京1株和兰州1株共30株在一个进化分支上,同源性也高达99.3%。本研究有助于监测PCV-2的疫源和进化关系,为进一步深入研究福建省生猪猪圆环病毒来源奠定一定基础。     

猪细小病毒LDR-PCR检测方法的建立和应用

为准确特异灵敏地检测猪细小病毒(PPV),建立一种新的LDR-PCR方法。首先在病毒的保守区内设计一对LDR探针,LDR探针两端各连有一段引物对应序列,以连接产物为模板进行PCR,琼脂糖凝胶电泳检测结果。以标准质粒为模板,通过对LDR反应的退火温度、连接酶浓度及探针浓度等反应条件进行优化,确定了LDR最佳的反应体系,并建立了LDR-PCR方法。结果表明,可以特异地检测PPV,与猪繁殖与呼吸障碍综合征病毒(PRRSV)、猪瘟病毒(CSFV)、伪狂犬病毒(PRV)、猪圆环病毒(PCV)、猪传染性胃肠炎病毒(TGEV)、猪流行性腹泻病毒(PEDV)无交叉反应;最低检测限为102个拷贝。利用建立的方法对41例临床样本进行检测,14份样品PPV阳性,与普通PCR检测结果符合率为97.6%。     

Complete genome sequence of the first canine circovirus

We found a highly divergent circovirus in serum samples from several dogs. Phylogenetic analysis indicates that canine circovirus genotype 1 (CaCV-1) represents the first circovirus reported in dogs and is genetically most closely related to the only known mammalian circovirus, porcine circovirus. Here we report the complete genome sequence of the CaCV-1 strain NY214, which will help toward understanding the evolutionary and pathogenic characteristics of mammalian circoviruses.     

Prevalence of infection and genetic diversity of porcine circovirus type 2 (PCV2) in wild boar (Sus scrofa) in Poland

Porcine circovirus type 2 (PCV2) is a widespread, important pathogen of domestic swine and the causative agent of postweaning multisystemic wasting syndrome and other diseases and conditions referred to as "porcine circovirus diseases." Specific antibodies and DNA to PCV2 have also been detected in European wild boars and North American feral pigs. We collected 312 tonsil samples from wild boars shot in 13 of 16 districts of Poland, and tested them for PCV2 DNA using a real-time PCR. We detected PCV2 DNA in 75.6% of tested tonsils, and in particular, in 60% of samples from the 2006-07 season, and 91% from 2007-08. The phylogenetic analysis that included 12 PCV2 sequences from wild boars revealed that they belonged to two genetic clusters, PCV2b and PCV2a. We present data on prevalence of PCV2 in Polish wild boars and for the first time report the PCV2a genotype in Poland.